Robert Hooke first named cells when he built a simple microscope and observed thin sections of cork. This is what he saw. The Cell theory states that:
All Living organisms are made up of cells or the products of cells
Cells are the units of life
All cells come from pre-existing cells.
Plant cells and Animal cells differ in three ways:
Plant cells have cell walls made of cellulose (structural carbohydrate)
Plant cells usually contain chloroplasts - tiny organelles that contain chlorophyll, which allows plants to convert the sun's energy into glucose and carbohydrates.
Plant cells usually have a large vacuole, containing water and dissolved minerals.
Cells vary in size
The smallest are bacterial cells (about 3 microns) up to some plant cells of 100 microns.
In humans, red blood cells are very small, and some nerve cells are very long.
The Cell theory states that:
- All Living organisms are made up of cells or the products of cells
Cells are the units of lifeAll cells come from pre-existing cells.
Plant cells and Animal cells differ in three ways:
Plant cells usually contain chloroplasts - tiny organelles that contain chlorophyll, which allows plants to convert the sun's energy into glucose and carbohydrates.
Plant cells usually have a large vacuole, containing water and dissolved minerals.
Links to great Cell sites:
Biology 4 Kids - Cells - http://www.biology4kids.com/files/cell_main.htmlCells Alive - an interactive web site
Virtual microscope - red blood cell smear - http://medsci.indiana.edu/a215/virtualscope/virtual/blood_smr_vd.html
Close up of blood cells - http://medsci.indiana.edu/a215/virtualscope/docs/chap7_1.htm
Cell Biology clip (You Tube) - http://www.youtube.com/watch?v=emhsevtm0YI
3D Cell Explorer animations of cell processes.
The Virtual Electron Microscope - a lesson plan from Discovery Education.